Valve arrangement

ABSTRACT

The invention concerns a valve arrangement ( 7 ) comprising a flow path ( 11 ) connecting an inlet ( 9 ) and an outlet ( 10 ), a closing means ( 12 ) arranged in said flow path ( 11 ), a resetting means and a first pressure in a first pressure chamber ( 14 ) acting in a closing direction on said closing means ( 12 ), a pressure of said outlet ( 10 ) and a second pressure in a second pressure chamber ( 18 ) corresponding to a pressure of said inlet ( 9 ) when said closing means ( 12 ) is closed acting in opening direction on said closing means ( 12 ), said first pressure chamber ( 14 ) being connectable to the outlet ( 10 ) via an auxiliary valve ( 13 ). It is intended to keep small a pressure pulse when opening the valve arrangement ( 7 ). This is achieved in that the closing means ( 12 ) having a first opening state (A) and a second opening state (B), a flow resistance of said closing means ( 12 ) in said first opening state (A) being larger than a flow resistance of said closing means in said second opening state (B).

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. patentapplication Ser. No. 12/785,727 filed May 24, 2010, which is entitled tothe benefit of European Patent Application No. 09007191.1 filed on May29, 2009, the contents of both are incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The invention concerns a valve arrangement comprising a flow pathconnecting an inlet and an outlet, a closing means arranged in said flowpath, a resetting means and a first pressure in a first pressure chamberacting in a closing direction on said closing means, a pressure of saidoutlet and a second pressure in a second pressure chamber correspondingto a pressure of said inlet when said closing means is closed acting inopening direction on said closing means, said first pressure chamberbeing connectable to the outlet via an auxiliary valve.

BACKGROUND OF THE INVENTION

Such a valve arrangement is known from WO 2005/031202 A1.

The closing means forms a pilot controlled valve means. Such a valvemeans is particularly used in connection with a control of water, whichis exposed to a high pressure. Applications are, for example, snowgenerating devices and moistening devices.

A snow generating device is used as example for illustrating the presentinvention. However, the invention is not limited to a valve arrangementin connection with a snow generating device.

A snow generating devices uses water which is supplied with a ratherhigh pressure of 20 to 120 bar. This water is atomised and sprayed intocold air in order to produce snow. When the snow generating device isnot in use, it must be emptied in order to avoid damages caused byfrozen water.

When the operation of the snow generating device starts, the valvearrangement is opened by actuating the pilot valve. However, since thewater is supplied to the empty snow generating device with the abovementioned high pressure in the range of 20 to 120 bar, a pressure pulseis generated in the snow generating device which can be detrimental.

SUMMARY OF THE INVENTION

The invention is based on the task to keep a pressure pulse small whenopening the valve arrangement.

With a valve arrangement as mentioned in the introduction this task issolved in that said closing means having a first opening state and asecond opening state, a flow resistance of said closing means in saidfirst opening state being larger than a flow resistance of said closingmeans in said second opening state.

When the valve arrangement opens to connect the pressure source with thesnow generating device, the water is in a first step supplied via theclosing device in the first state. The closing device has a rather highflow resistance so that a corresponding large pressure drop occurs overthe closing device. Nevertheless, the closing device is filled withwater and the pressure in the snow generating device increases. When thesnow generating device is completely filled or other conditions are met,the closing device opens to the second opening state so that the supplyof water is no longer restricted as before. The flow resistance of theclosing device in the second opening state is far lower than in thefirst opening state. During operation of the snow generating device apermanent supply of water under high pressure is required. The supplycan be realised since the closing device in the second opening state hasonly a rather low flow resistance. If the valve arrangement is not usedin connection with a snow generating device, any other suitablehydraulic fluid can be used. In the following the invention isillustrated using water as an example of an hydraulic fluid. However,the invention is not limited to water as hydraulic fluid.

In a preferred embodiment the second opening state of said closing meansis established by a pressure at the outlet which exceeds a predeterminedvalue. In other words, the valve arrangement is self-controlled. Thewater supplied to the snow generating device fills the snow generatingdevice increasing the pressure at the outlet. When the predeterminedpressure value is reached, the valve arrangement “knows” that it now canfully open and supply water without having the risk of a strong pressurepulse in an empty system.

Advantageously said resetting means comprises at least a spring. Aspring is a rather simple embodiment of a resetting means. It has theadvantage that the spring force increases when the spring is compressed.This characteristic can be used to establish the different openingdegrees or opening states of the closing means.

It is advantageous that said closing means comprises at least a firstvalve element and a second valve element. Using at least two valveelements gives a rather simple construction of the valve arrangement inwhich two different opening conditions can be established.

Preferably said first pressure chamber and said second pressure chamberare connected via an orifice running through said first valve element.In dependence of the position of the first valve element water issupplied from the second pressure chamber to the first pressure chamber.It is therefore possible to create a sufficient pressure in the firstpressure chamber to move the first valve element from an openingposition to a closing position in case the valve arrangement shouldclose. Since the orifice is arranged in the valve element it is notpossible that this orifice is closed by a movement of said first valveelement.

Preferably the first valve element together with a first valve seatforms a valve means, the second valve element together with a secondvalve seat forms a throttling means and the valve means and thethrottling means are connected in series. When the valve means opens,the flow of water is restricted by the throttling means. Only when thethrottling means opens too, the flow of water is almost unrestricted.This is a rather simple construction of the valve arrangement.

Preferably said first valve element is slidingly arranged around saidsecond valve element, said second valve element protrudes through saidfirst valve seat, and said second valve seat is formed by a ring bearingsaid first valve seat. Such an embodiment allows a rather compactconstruction. A gap between the second valve element and the secondvalve seat forms the throttling means. It is possible to determine thethrottling characteristics of this throttling means by forming thesecond valve element and/or the second valve seat with correspondinggeometries.

Preferably a first spring acts on said first valve element and a secondspring acts on said second valve element. In this manner it is possibleto make the closing means so that the movement of the first valveelement requires a smaller force than the movement of the second valveelement. Since the second valve element moves in opening direction underthe control of the pressure at the outlet, the second spring can bedimensioned depending on the predetermined pressure at which the closingdevice should be brought into the second opening state.

Preferably said second valve element comprises a moving restrictorstopping a movement of said second valve element in closing direction.Such a moving restrictor can be made by a step or any other protrusionabutting against a part of the housing in which the second valve elementis arranged. Such a second valve element can be positioned in the secondvalve seat with a rather high precision.

In another preferred embodiment said first pressure chamber is connectedwith said outlet via a second orifice, and said second valve elementtogether with a second valve seat is forming a second valve meansarranged parallel to said second orifice. Since the second pressurechamber and the first pressure chamber are connected via the firstorifice, the first orifice and the second orifice form a pressuredivider when the auxiliary valve is opened. This means that in the firstpressure chamber a pressure is established which is between the pressureat the inlet and the pressure at the outlet. This “medium” pressure actsin closing direction on the first valve element so that the first valveelement is moved only a short distance away from the first valve seatuntil this medium pressure together with the force of the resettingmeans has an equilibrium to the force generated by the pressure of theoutlet. This allows only a restricted flow of water through the gapbetween the first valve element and the first valve seat. When thesecond valve is open, the first pressure chamber is connected to theoutlet without the second orifice. Therefore, the pressure in the firstpressure chamber is lowered so that the pressure at the outlet can movethe first valve element to the fully opened state.

Preferably said second valve element is actuatable by a pressure at saidoutlet. When the pressure at the outlet reaches the predetermined value,the second valve is opened connecting automatically the first pressurechamber with the outlet so that the closing means is automatically movedto the fully opened state.

In another preferred embodiment a third valve means is arranged betweensaid inlet and said outlet opening a restricted flow passage when it isloaded by said first pressure in said first pressure chamber whichloading is controlled by said auxiliary valve. The third valve means isa kind of pre-filling means by which water (or like in all otherembodiments any other fluid) can flow from the inlet to the outletwithout causing a pressure pulse in the empty outlet. This allows acontrolled increase of the pressure in the outlet. When the outlet andthe snow generating means are filled sufficiently with water, theclosing means can fully open to supply the outlet and the snowgenerating device with the required flow of water.

Preferably said second valve element opens a passage between the firstpressure chamber and said outlet when the pressure at said outletexceeds a predetermined value. The second valve element is openedautomatically when the outlet and the snow generating device are filledsufficiently with water so that a pressure pulse in an empty or onlypartly filled system can be avoided. When the first pressure chamber isconnected to the outlet, the first valve element can be moved away fromthe first valve seat since the pressure in the first pressure chamber issufficiently low and the pressure at the inlet acts in opening directionon the first valve element. No further action from the outside isrequired.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is explained in detail on the basis ofpreferred embodiments in connection with the drawings, showing:

FIG. 1A is a schematic illustration of an hydraulic circuit,

FIG. 1B shows a graph of the pressure P over the time t at the outlet,

FIG. 1C shows a slightly modified embodiment of the valve arrangementshown in FIG. 1A,

FIG. 2 shows a first embodiment of a valve arrangement with a closingmeans in fully closed state,

FIG. 3 shows said valve arrangement with the closing means in partlyopened state,

FIG. 4 shows said valve arrangement with the closing means in fullyopened state,

FIG. 5 shows said valve arrangement during closing of the closing means,

FIG. 6 is a second embodiment of the valve arrangement, and

FIG. 7 is a schematic illustration of a third valve arrangement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A shows an hydraulic circuit 1 supplying a snow generating device2 with water under high pressure. The snow generating device 2 comprisesnozzles 2 a through which the water is outputted generating waterdroplets or a water mist. Therefore, in operation the snow generatingdevice has a permanent water requirement. A pump 3 driven by a motor 4generates a pressure in the range of 20 bar or more. The pressure islimited by a safety valve 5 having an opening pressure of 110 bar forexample. When the safety valve 5 opens, water is drained to a tank 6.The pump 3 can be replaced by any other pressure generating device, e.g.a tank or a reservoir being arranged higher than the snow generatingdevice 2.

The snow generating device 2 is connected to the pump 3 via a valvearrangement 7. Furthermore, it is connected to the tank 6 via a drainingvalve 8. When the snow generating device is not in use, the drainingvalve 8 is opened to let the water come out in order to avoid damages byfrozen water in the snow generating device.

When the snow generating device 2 is empty, i.e. more or less completelyfilled with air, it is dangerous to supply the water from the pump 3with full pressure. In this case, a pressure pulse would be generatedwith the risk to damage the snow generating device 2.

The valve arrangement 7 comprises an inlet 9 and an outlet 10 which areconnected by a flow path 11.

A closing means 12 is arranged in said flow path 11, said closing meanshaving a fully closed condition. This condition is shown in the Fig.Furthermore, said closing means has a first opening state A and a secondopening state B. The flow resistance of said closing means 12 in saidfirst opening state A is larger than the flow resistance of the saidclosing means 12 in said second opening state B. In other words, theclosing means 12 is fully opened in the second opening state B andpartly opened in the said first opening state A. FIG. 1B shows thepressure P over the time t at the outlet. Pressure P1 is the outletpressure of pump 3. From time t1 to time t2 the closing means 12 is onlypartly opened so that the pressure can only increase slowly from zero toa pressure P2. At time t2 the closing means 12 is opened to the fullyopened condition B so that the pressure is rapidly increased to apressure value P3. This pressure value P3 is maintained constant untilthe closing means 12 is fully closed.

The increase from pressure P2 to pressure P3 is performed when the snowgenerating device 2 is completely or almost completely filled with waterso that no air or only small volumes of air are compressed by theincoming water. From time t2 to time t3 water is supplied withsufficient pressure and sufficient flow in order to enable the snowgenerating device 2 to produce snow.

In order to open the valve arrangement 7 an auxiliary valve 13 isarranged between the inlet 9 and the outlet 10 parallel to the closingmeans 12. A first pressure chamber 14 is connected via a first orifice15 with the inlet 9. Therefore, when the closing means 12 is closed, inthe first pressure chamber 14 there is a first pressure corresponding tothe pressure at the inlet 9. This first pressure in said first pressurechamber 14 acts in closing direction on said closing means 12.Furthermore, a resetting means in form of a spring 16 also acts inclosing direction on said closing means 12.

The first pressure chamber 14 is connected to the outlet 10 via theauxiliary valve 13 and a second orifice 17. When the auxiliary valve 13opens, the first pressure in said first pressure chamber 14 will be anintermediate pressure between the pressure at said inlet 9 and saidoutlet 10.

Said inlet 9 is connected to a second pressure chamber 18. The pressurein said pressure chamber 18 (“the second pressure”) acts in openingdirection on the closing means 12. Additionally, the outlet 10 isconnected to a third pressure chamber 19. Therefore, the pressure at theoutlet 10 acts in opening direction on said closing device 12.

The operation of said valve arrangement can be described at follows:

When the auxiliary valve 13 is closed, the first pressure in the firstpressure chamber 14 together with the resetting means (spring 16) movethe closing means 12 in fully closed condition. No further water issupplied to the snow generating device 2. The snow generating device 2can be emptied via the draining valve 8.

When the snow generating device 2 is started, the draining valve 8 isclosed. The auxiliary valve 13 is opened. The first pressure in thefirst pressure chamber 14 is lowered via the second orifice 17. Thepressure difference between the second pressure chamber 18 and the firstpressure chamber 14 exceeds the force of the spring 16, so that theclosing means 12 is moved into the first opening state A, i.e. into apartly opened condition. A further movement is not possible at thismoment since the closing means 12 is stopped by a stop 20 which issupported by a second spring 21.

Nevertheless, water flows through the flow path 11 from the inlet 9 tothe outlet 10 increasing the pressure at the outlet 10. This pressureincrease in the third pressure chamber 19 increases the force acting inopening direction on the closing means 12. When a predetermined pressureP2 is reached in the outlet 10, the pressure difference between thethird pressure chamber 19 and the first pressure chamber 14 exceeds theforce of the second spring 21 so that the closing means 12 is fullyopened, i.e. brought into the second opening condition in which thewater can flow more or less unrestricted through the flow path 11. Onlya small pressure drop appears across the closing means 12.

When the valve arrangement is to be closed, the auxiliary valve 13closes. The first pressure in the first pressure chamber 14 increases tothe outlet pressure P1 of the pump. The effective pressure area in thefirst pressure chamber 14 is larger than the effective area in thesecond pressure chamber 18. Therefore, the closing means 12 is closed.

FIG. 1C shows a slightly modified valve arrangement 7 in which a chamberin which the second spring 21 is arranged is open to atmosphere. Allother elements are the same.

FIGS. 2 to 5 show a first embodiment of said valve arrangement 7 withmore details.

The same elements as in FIG. 1A are designated with the same numerals.

The inlet 9 and the outlet 10 are arranged in a housing 22 forming afirst valve seat 23 and a second valve seat 24. The second valve seat 24is formed at the radial inner part of a ring section 25 of the housing22 bearing the first valve seat 23.

A first valve element 26 together with said first valve seat 23 form avalve means. When the first valve element 26 is in contact with thefirst valve seat 23, the valve arrangement 7 is fully closed.

A second valve element 27 protrudes through said second valve seat 24and together with said second valve seat 24 form a throttling means. Inother words, there is a small gap between the second valve element 27and the second valve seat 24. When the first valve element 26 is movedaway from the first valve seat 23 (opening the valve means) the flow ofwater from the inlet 9 to the outlet 10 is throttled by the throttlingmeans.

The inlet 9 is connected to the second pressure chamber 18. The outlet10 is connected to the first pressure chamber 14 via the auxiliary valve13. The auxiliary valve 13 comprises an electromagnet 28. The auxiliaryvalve 13 is arranged in a channel 29 connecting the second pressurechamber 18 and the outlet 10.

The first spring 16 acts on the first valve element 26 in closingdirection. The second spring 21 acts on the second valve element 27 inclosing direction. The second valve element 27 comprises a movingrestrictor 30 bearing against the housing 22 when the throttling meansexhibits the largest flow restriction. The second spring 21 is arrangedin a spring chamber which opens to atmosphere.

The second spring 21 is a resetting means. However, other means can beused to generate a resetting force, e.g. an external fluid pressure(liquid or gas), a motor or a lever loaded from the outside.

The pressure in the first pressure chamber 14 acts on a first pressurearea 31. The pressure in the second pressure chamber 18 acts on a secondpressure area 32. The second pressure area 32 is larger than the firstpressure area 31.

The first valve element 26 is slidingly arranged around the second valveelement 27, i.e. it forms a hollow cylinder, the inner diameter of whichcorresponds to the outer diameter of the second valve element 27.Sealing means 33 are provided to prevent a flow of water between thefirst valve element 26 and the second valve element 27.

An orifice 34 is provided in the first valve element 26 connecting thefirst pressure chamber 14 and the second pressure chamber 18, i.e. thefirst pressure chamber 14 and the inlet 9. This orifice 34 correspondsto the orifice 15 of FIG. 1A.

The operation of this valve arrangement 7 is explained in connectionwith FIGS. 2 to 5.

It is assumed that the snow generating device 2 has been drained.Therefore, the pressure at the outlet 10 is very low. When the auxiliaryvalve 13 is opened, the first pressure in the first pressure chamber 14is lowered almost to the pressure value at the outlet 10. The pressurein the second pressure chamber 18 is the pressure at the inlet 9.Although the first pressure area 31 in the first pressure chamber 14 islarger than the second pressure area 32 in the second pressure chamber18, the force acting in the opening direction on the first valve element26 exceeds the force of the first spring 16 moving the first valveelement 26 away from the first valve seat 23. This condition is shown inFIG. 3. In FIGS. 3 to 5 elements of the auxiliary valve 13 have beenomitted.

When the first valve element 26 has been moved away from the first valveseat 23, the flow of water from the inlet 9 to the outlet 10 isrestricted by the throttling means formed by the second valve element 27and the second valve seat 24, i.e. the water flows through a gap betweenthe second valve element 27 and the second valve seat 24. This gap canbe shaped ring-like having a radial thickness of 15/100 mm, for example.It may be smaller or larger depending on the application and the desiredflow restriction. The throttling characteristic of this throttling meanscan be adjusted by designing the form of the second valve seat 24 andthe form of the second vale element 27.

Water flowing from the inlet 9 to the outlet 10 will increase thepressure at the outlet 10. When the pressure at the outlet 10 exceeds apredetermined value, the force on the second valve element 27 generatedby the pressure at the outlet 10 exceeds the force generated by thesecond spring 21 so that the second valve element 27 is moved out of thesecond valve seat 24 fully opening the connection between the inlet 9and the outlet 10. This condition is shown in FIG. 4.

The first pressure chamber 14 receives permanently water from the inlet9 via the orifice 34. However, this water escapes through the channel 29to the outlet 10 as long as the auxiliary valve 13 is open.

When the auxiliary valve 13 is closed, the first valve element 26 by thepressure in the first pressure chamber 14 is moved back to the firstvalve seat 23 closing the valve means 7. For a short time the secondvalve element 27 remains out of the second valve seat 24 (FIG. 5).However, since no further water is supplied from the inlet 9 to theoutlet 10, the pressure at the outlet 10 drops and the second spring 21will move the second valve element 27 back to the condition shown inFIG. 2.

FIG. 6 shows a second embodiment of a valve arrangement 7 in which likeelements as in FIG. 1A to 5 are designated with the same numerals.

In the condition shown the valve arrangement 7 is fully closed. Thefirst valve element 26 together with the first valve seat 23 seal aconnection between the inlet 9 and the outlet 10.

The first pressure chamber 14 is connected via a second orifice 35 andthe auxiliary valve 13 to the outlet 10.

In the initial state (valve arrangement fully closed) the first pressurein the first pressure chamber 14 equals the pressure at the inlet 9. Thepressure at the outlet 10 is almost zero. The first pressure area 31 ismuch larger than the second pressure area 32.

When the auxiliary valve 13 opens, a flow is established between theinlet 9 and the outlet 10 via the two orifices 34, 35. Therefore, thefirst pressure in the first pressure chamber 14 drops to an intermediatevalue between the pressure at the inlet 9 and the pressure at the outlet10. The orifices 34, 35 are so designed that the force difference overthe first valve element 26 which is generated by the pressure in thefirst pressure chamber 14 acting on the first pressure area 31 and thepressure in the second pressure chamber 18 acting on the second pressure32 exceeds slightly the force of the first spring 16. However, the forcedifference is only slightly larger than the force of the first spring26. Therefore, an equilibrium is reached when the first valve element 26is moved away from the first valve seat 23 by a small distance in therange of a few millimetres or less. In this condition, a restricted flowfrom the inlet 9 to the outlet 10 is possible. This flow increases thepressure at the outlet 10.

The second valve element 27 together with the second valve seat 24 forma second valve means which is arranged parallel to the second orifice35. The second valve element 27 is forced against the second valve seat24 by means of the second spring 21. The pressure in the channel 29which corresponds to the pressure at the outlet 10 acts on a pressurearea 36 of the second valve element 27.

When the pressure at the outlet 10 has reached a predetermined value,the force generated by this pressure (transmitted via the channel 29 tothe second valve element 27) acting on the pressure area 36 of thesecond valve element 27 exceeds the force of the second spring 21, andthe second valve means is open since the second valve element 27 ismoved away from the second valve seat 24. In this case, the pressure inthe first pressure chamber 14 drops further to the pressure value at theoutlet 10. The pressure difference over the first valve element 26 nowis big enough to compress the first spring 16 completely so that thefirst valve element 26 is moved further away from the first valve seat23, and the valve arrangement 7 fully opens.

When the auxiliary valve 13 closes, the first pressure in the firstpressure chamber 14 increases since water is permanently supplied viathe orifice 34. Since at the same time the pressure at the outlet 10drops, the first valve element 26 is moved back to contact the firstvalve seat 23 to close the valve arrangement 7.

FIG. 7 shows a further embodiment of a valve arrangement 7. Likeelements as in FIGS. 1 to 6 are designated with the same numerals.

In the condition shown in FIG. 7 the valve arrangement 7 is fullyclosed. The first valve element 26 together with the first valve seat 23stop any flow from the inlet 9 to the outlet 10. The first pressure inthe first pressure chamber 14 corresponds to the pressure at the inlet 9since the inlet 9 is connected to the first pressure chamber 14 by thefirst orifice 34.

A third valve means 37 is provided having a third valve element 38arranged in a bore 39. The third vale element 38 comprises acircumferential grove 40. The bore 39 intersects an auxiliary channel41. A third spring 43 acts on the third valve element 38 in order tobring the grove 40 out of overlap with the auxiliary channel 41.Therefore, the auxiliary channel 41 between the inlet 9 and the outlet10 is closed.

When the auxiliary valve opens, the first pressure in the first pressurechamber 14 acts on the third valve element 38 in opening direction andmoves the third valve element 38 so that the grove 40 overlaps theauxiliary channel 41. Therefore, a flow of water is established betweenthe inlet 9 and the outlet 10. The first valve element 26 restingagainst the first valve seat 23. The flow of water through the auxiliarychannel 41 is restricted by the third valve means 37, i.e. the pressurein the outlet 10 increases only slowly by a kind of prefilling.

The second valve element 27 likewise comprises a circumferential grove43. The second spring 21 shifts the second valve element 27 within abore 44 to bring the grove 43 out of overlapping with an channel 45.

When the pressure in the outlet 10 generates a force on the second valveelement 27 exceeding the force of the second spring 21, the second valveelement 27 is moved so that the grove 43 overlaps the channel 45. Thisoverlapping establishes a connection from the first pressure chamber 14via the channel 29 and the channel 45, the auxiliary valve 13 and thechannel 45 to the outlet 10. The first pressure in the first pressurechamber 14 rapidly drops so that this first pressure together with theforce of the first spring 16 is no longer able to withstand the forcegenerated by the pressure in the second pressure chamber 18 acting onthe second pressure area 32 of the first valve element 26. The firstvalve element 26 is moved away from the first valve seat 23 against theforce of the first spring 16, and the valve arrangement is fully opened.

When the valve arrangement 7 is to be closed, the auxiliary valve 13 isclosed so that the first pressure in the first pressure chamber 14increases to the pressure at the inlet 9 via the orifice 34, and thefirst valve element 26 is moved back to contact the valve seat 23.

While the present invention has been illustrated and described withrespect to a particular embodiment thereof, it should be appreciated bythose of ordinary skill in the art that various modifications to thisinvention may be made without departing from the spirit and scope of thepresent invention.

What is claimed is:
 1. A valve arrangement comprising a flow pathconnecting an inlet and an outlet, a closing means arranged in said flowpath, a resetting means and a first pressure in a first pressure chamberacting in a closing direction on said closing means, a pressure of saidoutlet and a second pressure in a second pressure chamber correspondingto a pressure of said inlet when said closing means is closed acting inan opening direction on said closing means, said first pressure chamberbeing connectable to the outlet via an auxiliary valve, wherein theclosing means has a first opening state and a second opening state, aflow resistance of said closing means in said first opening state beinglarger than a flow resistance of said closing means in said secondopening state, wherein said closing means is moved into the firstopening state by a pressure difference between the second pressurechamber and the first pressure chamber, and wherein said closing meansis moved from the first opening state to the second opening state by apressure at the outlet which exceeds a predetermined value.
 2. The valvearrangement according to claim 1, wherein said resetting means comprisesat least a spring.
 3. The valve arrangement according to claim 1,wherein said closing means comprises at least a first valve element anda second valve element,
 4. The valve arrangement according to claim 3,wherein said first pressure chamber and said second pressure chamber areconnected via an orifice running through said first valve element. 5.The valve arrangement according to claim 3, wherein said first valveelement together with a first valve seat form a valve means, said secondvalve element together with a second valve seat form a throttling means,and the valve means and the throttling means are connected in series. 6.The valve arrangement according to claim 5, wherein said first valveelement is slidingly arranged around said second valve element, saidsecond valve element protrudes through said first valve seat, and saidsecond valve seat is formed by a ring bearing said first valve seat. 7.The valve arrangement according to claim 3, wherein the resetting meanscomprises a first spring acting on said first valve element in theclosing direction and a second spring acting on said second valveelement in the closing direction.
 8. The valve arrangement according toclaim 3, wherein said second valve element comprises a moving restrictorstopping a movement of said second valve element in closing direction.9. The valve arrangement according to claim 1, wherein said firstpressure chamber is connected with said outlet via a second orifice, andsaid second valve element together with a second valve seat are forminga second valve means arranged parallel to said second orifice.
 10. Thevalve arrangement according to claim 9, wherein said second valveelement is actuatable by a pressure at said outlet.
 11. The valvearrangement according to claim 1, wherein a third valve means isarranged between said inlet and said outlet opening a restricted flowpassage when it is loaded by said first pressure in said first pressurechamber which loading is controlled by said auxiliary valve.
 12. Thevalve arrangement according to claim 11, wherein said second valveelement opens a passage between said first pressure chamber and saidoutlet when the pressure at said outlet exceeds a predetermined value.13. A valve arrangement comprising: a flow path connecting an inlet andan outlet; a closing means arranged in said flow path, the closing meansincluding a first opening state and a second opening state, a flowresistance of said closing means in said first opening state beinglarger than a flow resistance of said closing means in said secondopening state; a resetting means biasing the closing means in a closingdirection, a first pressure chamber connected to the inlet, the firstpressure chamber configured such that a first pressure in the firstpressure chamber acts in the closing direction on said closing means; asecond pressure chamber connected to the inlet, the second pressurechamber configured such that a second pressure in the second pressurechamber acts in an opening direction on said closing means; a thirdpressure chamber in connection with the outlet, the third pressurechamber configured such that a third pressure in the third pressurechamber acts in an opening direction on said closing means; and anauxiliary valve connecting the first pressure chamber to the outlet, theauxiliary valve being movable between a closed state and an open state;wherein the auxiliary valve is configured such that in an open state,the first pressure in the first pressure chamber decreases, therebycreating a pressure difference between the second pressure chamber andthe first pressure chamber which overcomes the resetting means biasingthe closing means in a closing direction and moves the closing meansinto the first opening state; wherein the auxiliary valve is configuredsuch that in an open state, a pressure at the outlet increases, therebyincreasing the third pressure at the third pressure chamber and creatinga pressure difference between the third pressure chamber and the firstpressure chamber which overcomes the resetting means biasing the closingmeans in a closing direction and moves the closing means into the secondopening state.
 14. The valve arrangement according to claim 13, whereinthe second opening state of said closing means is established by apressure at the outlet which exceeds a predetermined value.
 15. Thevalve arrangement according to claim 13, wherein said closing meanscomprises at least a first valve element and a second valve element, 16.The valve arrangement according to claim 15, wherein said first pressurechamber and said second pressure chamber are connected via an orificerunning through said first valve element.
 17. The valve arrangementaccording to claim 15, wherein the resetting means comprises a firstspring acting on said first valve element in the closing direction and asecond spring acting on said second valve element in the closingdirection.
 18. The valve arrangement according to claim 17, wherein theclosing means moves into the second opening state when the pressuredifferential between the third pressure at the third pressure chamberand the first pressure at the first pressure chamber is sufficient toovercome the second spring acting on the second valve element in theclosing direction.
 19. A valve arrangement comprising a flow pathconnecting an inlet and an outlet, a closing means arranged in said flowpath, a resetting means and a first pressure in a first pressure chamberacting in a closing direction on said closing means, a pressure of saidoutlet and a second pressure in a second pressure chamber correspondingto a pressure of said inlet when said closing means is closed acting inan opening direction on said closing means, said first pressure chamberbeing connectable to the outlet via an auxiliary valve, wherein theclosing means has a first opening state and a second opening state, aflow resistance of said closing means in said first opening state beinglarger than a flow resistance of said closing means in said secondopening state, wherein said first pressure chamber is connected withsaid outlet via a second orifice, and said second valve element togetherwith a second valve seat are forming a second valve means arrangedparallel to said second orifice.
 20. The valve arrangement according toclaim 19, wherein said second valve element is actuatable by a pressureat said outlet.